Forty newly diagnosed, drug naive adult epileptic patients were evaluated for cognitive effects of phenytoin (DPH) and carbamazepine (CBZ). They were randomized into DPH and CBZ groups. Patients with space occupying lesions, progressive degenerative, metabolic and active central nervous system infections were excluded from the study. None of the patients had seizures during the study period. Both the groups were comparable for age, duration as well as type of epilepsy. Full cognitive assessment was carried out using a neuropsychological battery consisting of verbal and performance intelligence, memory, vasomotor function and dysfunction analysis tests before starting the anticonvulsant therapy. The same tests were repeated after 3 months. The mean serum levels of DPH and CBZ at the end of the study period were 19.42 ¤ 4.20 ug/ml and 9.45 ¤ 9.26 ug/ml respectively. The cognitive functions were compared between pre and post study periods in each group and between the two groups. The differences were correlated with serum drug levels. No significant difference in cognitive functioning was noticed in either of the study groups. There was no significant correlation with serum drug levels. It was concluded that both DPH and CBZ have no adverse effects on cognition in adult epileptics with normal therapeutic drug levels.